April 2012World Premiere!
Audioengine D2 24-Bit Wireless DACFits well with the needs of a 21st Century
audiophile.
Review By Tom Lyle

I guess it is natural for a reviewer
to desire or otherwise accept expensive and as close to state-of-the-art
equipment as possible for review. I'm certainly guilty of this. And can you
blame me? Not everyone can afford to purchase the mega-buck equipment that is
often produced, and who better than one that has heard more than his share of
equipment over the years to share his experience with the rest of the audiophile
world? But honestly, it gives me just as much pleasure to come across gear that
almost anyone involved in this pursuit can afford that performs well above
what's expected, and at the same time is musically satisfying – that's what it
is all about, really.

In the case of the Audioengine D2 wireless
digital-to-analog converter, this affordable (no quotes, because it's actually
affordable) piece of gear allows us busy audiophiles to enjoy as high as
24-bit/96kHz sample rate music sourced from our computer in any system around
the house – without the use of a home network. The D2 is a two unit affair
that comes packaged with a "sender" and a "receiver". Audioengine claims
bit-perfect PCM stereo transmission routed from either the transmitter connected
to a host computer's USB output or via an optical connection from a source
connected directly to the receiver. The sender can beam a wireless signal to the
one receiver that comes in the standard package, or to as many as three
Audioengine D2 receivers. They go on to say that there are many disadvantages to
using a wired system, such as jitter, grounding, and cable noise are minimized
with a wireless system, not to mention the noise generated by the computer
itself. The D2 uses a Texas Instruments USB controller chip, which has found its
way into many high-end USB products. The sender can be powered by either a
provided power supply which is connected to an AC wall outlet or directly from
the USB bus. This USB power is passed through two stages of regulation that
Audioengine says ensures high stability and low noise. The receiver uses a
PCM1792 DAC because it also has a reputation for having low noise and high sound
quality.

In regards to the question whether the D2 USB is
isochronous or asynchronous, is that the D2 uses what's called "adaptive mode"
in its USB receiver, which will read the data coming from the computer and
adjust it so as to not miss any data. Because the transmission between the
sender and receiver is wireless, the data becomes asynchronous before it arrives
at the receiver. This is a good thing, as the D2 behaves as an asynchronous USB
digital-to-analog converter and is 24-bit/96kHz bit-perfect, even in its
wireless transmission.

PhysicalBut
let's put aside the D2's technical claims for a bit to discuss the physical.
First of all, there are no driver(s) that need to be installed on the host
computer for the D2 to function. The Audioengine D2 is in all senses of the term
a plug-and-play device. The lengthiest portion of the set-up procedure was
walking down the two flights of stairs to the system in which I connected the
receiver. I had the D2 up and running in about five minutes, max. The D2 set
comes packaged with all the cables one is likely to need to get started – a
USB cable to connect the sender to the host, power supplies and cables for both
units and even an RCA to RCA interconnect for the receiver to audio system
connection. The sender and receiver come packaged with gray "microfiber"
drawstring bags.

The front panel of the sender has a volume
control on its left-center portion. The D2 incorporates a separate-path wireless
channel to transmit volume information, and this volume information never
affects the digital audio stream. There is an optical input immediately to the
right of the volume control knob for those times when wanting to connect another
digital source to the sender. Next to this is the USB input, and then the input
for the power supply. The sender can also be powered by the USB input, and since
most new computers, that is, those less than three years-old have "clean" USB
power and should hear no difference between it and the external supply (as I
experienced). The folks at Audioengine said that since there is conditioning and
filtering on-board the D2 sender and receiver, the sound should be the same
either way it is powered. On the far left on the sender's front panel are two
small lighted switches labeled power and pair. The "pair" light blinks when it
doesn't sense the receiver, and is solid when it does. The only time I
experienced a blinking light is when the receiver was not connected. On the back
panel of the sender are two antennae for broadcasting the PCM signals to the
receiver.

The receiver has a pair of lighted switches on
the far left of its front panel labeled "power" and "pair". In the center there
are a pair of gold-plated RCA outputs, then the right of these is the optical
digital input, and then the power input. On the rear panel are the two antennae.
That's it. The two approximately five-inch by five-inch by one-inch silver-gray
boxes are modern looking devices that are far from obtrusive looking, and
super-easy to set up. Once they were up and playing music they did so without
problem, and never, ever needed to be "reset" or otherwise futzed with. I wish I
could say the same thing for the rest of my computer gear.

Host

I
connected the D2 sender to my host computer, a 3.20 GHz Dell Studio XPS PC with
8 gig of memory running Windows 7 with 4TB external hard disc space filled with
FLAC files, 98% of which are of the standard CD-quality 44.1/16-bit sample rate
variety. High-resolution files are increasing in number on my each of my drives
as we speak, but since the majority of the files were burned from my CD
collection that started logarithmically growing in size since the 1980s, the
huge number of files with this "low" resolution is hardly surprising. The system
where the D2 receiver was situated for most of the review period was located in
a common space in our home two floors away from the host computer. As more than
hinted at before, the D2 had absolutely no problem broadcasting an uninterrupted
signal between the two despite the relatively long distance. The power amps in
this system were tubed PrimaLuna monoblocks pumping out 70 wpc (in their ultra-linear
mode) first into a pair of Dynaudio 110 two-way stand-mounted speakers, and
later on into a pair of the most excellent Talon Hawk 2 two-ways that are bolted
onto their dedicated stands. The preamplifier was sometimes a tubed Balanced
Audio Technologies (BAT) VK-3iX, and sometimes a solid-state Edge G2 linestage.
For comparison's sake I connected the optical output of the D2 to a Benchmark
DAC1PRE or a CEntrance DACmini. All the gear is connected to a Panamax M5510-Pro
power conditioner, and interconnect, speaker, and power cables were all by DH
Labs, except the optical cable which was an inexpensive generic number.

As it is recommended in the D2's manual I let
this wireless DAC system break in for a while before being too critical in my
assessment of its sound quality. But to be honest I really didn't hear much
difference between the sample I was sent when it was fresh out of the box versus
its sound a month or so later. I was mightily impressed by not only the sound of
the D2, but almost more impressed in regards to how well the darn thing worked.
I used quite a few different sources from my computer that included iTunes,
Foobar 2000, VLC, and Internet radio streaming on either Firefox or Chrome, and
as long as my computer was working, that is, as long as there was music being
fed to the USB port music came through the D2's receiver and through the stereo
on the first floor. I also fed the D2 signals not only from my Squeezebox Touch
but from a disc player as well, and its sound varied little regardless of the
source, that is, as long as was comparing source material with the same
resolution.In a nutshell, the D2's sound was not as
proficient in its frequency extremes as the more than twice-the-price Benchmark
DAC1PRE – but the Benchmark is a different type of beast – it is a DAC,
headphone amp and preamplifier, not a wireless transmitter and receiver.

The sound of the Benchmark went deeper into the
bass, its soundstage was larger and more multilayered, its midrange was more
fleshed out and its treble more extended. Was its sound quality more than twice
as good as the Audioengine D2? No way – we're talking about the difference in
digital processors here, so even though it was not too difficult to hear the
differences between the two, these differences were not night and day. And as
good as the Benchmark sounds, the Audioengine D2 was not embarrassed by the
Benchmark. The Audioengine D2 was quite at home connected to this moderately
high-priced system – it was an extremely listenable DAC. I spent weeks with
the D2 hooked up to this system playing material of all genres fed from the
computer running Foobar 2000 on "shuffle tracks" mode. It was easy not to miss
the Benchmark that much, and that says a lot coming from me since I'm quite a
fan of this piece of gear.

As I sat in the rather large sweet spot in
between the Talon Hawk 2 speakers each and file or disc that I played through
the Audioengine D2 (that had decent sound quality to begin with) sounded
marvelous. Mahler's Third Symphony
is quite a challenging listen for many people, so I'm hardly recommending it for
the uninitiated. Yet on the standard 16-bit/44.1kHz FLAC sourced from the Telarc
CD that was recorded in the late 1990s, Jesus Lopez-Cobos coaxes from the very
talented players of the Cincinnati Symphony Orchestra one of my favorite
readings of this work. This version doesn't quite fit into what I find the
uncomfortable mold of "internationalization" of so many symphonic readings of
the last few decades before it, and as a result it makes this interpretation so
much more enjoyable. The Cincinnati players, especially the strings and horns
(and let's not forget the solo trombone), sound world class on this CD. The
Audioengine D2 is able to keep up with the recording in that it passes every
important element to the rest of the system, and especially the speakers to
create a lifelike representation (although in miniature) of the large forces
that make this lengthy piece so thrilling, and above all Lopez-Cobos and the
CSO's picturesque realization of the very complex, slowly unfolding score.

Although the system in which I used to audition
the D2 is not nearly state-of-the-art, it is probably more than a bit
sophisticated than those that most Audioengine customers are likely going to use
with their D2. Even though it was great to hear what the D2 was capable of,
sound quality-wise in this setting, most are going to use the D2 for what it was
designed for – moving one's music from their computer to another room in the
house with a small system. And this is also probably why Audioengine markets
some excellent, small self-powered speakers. I'm sure most of these speakers are
going to be used in desktop systems, which makes sense as they are perfectly
designed for the task, but I found that matching them with the D2 in a room that
doesn't normally have music was a magnificent experience. Audioengine was nice
enough to send me a pair of the D5+ two-way self-powered monitors to use with
the D2.

Without going too much into the D5+'s specifics,
they are beautifully made speakers, and at $399 for the pair quite amazing,
really. Their fit and finish is first rate, and I'm not just saying that to be
nice, they really are very well constructed little speakers. With a 5 inch
woofer, 0.75" silk dome tweeter, and on-board 50 Watt amplifier these
approximately 11" x 7" x 8" tykes can fit just about anywhere a "full-sized"
speaker can't, and I don't just mean flanking a computer's screen. I can't
describe the joy in not just have high-quality audio anywhere in the house I
wanted, but access to my entire digital library anywhere in the house that had
an AC outlet. I thought the speakers were voiced to vary a bit from perfectly
flat, but this was fine by me – the slightly elevated mid-bass and somewhat
scooped-out midrange gave the speakers a larger-than-life sound that fit in very
well into spaces that were, to say the least, not acoustically perfect. The
combination of the D2 wireless DAC and the A5+ powered speakers were about
$1000, and in my book it would be money well spent to have this kind of sound
quality combined with the convenience of wireless sound. Moving the three-piece
system (the two A5+ speakers and the D2 receiver) anywhere in the house that had
an AC outlet worked as reliably as hooking it up to the expensive system. It
worked without a hitch each and every time. There are no dead areas with my home
network within the house, as I couldn't find any areas within the house that the
D2 couldn't receive a good signal from its sender.

Remember

I'm
fairly sure that most readers are old enough to remember when the audiophile
world was first introduced to using computers as a tool to listen and manipulate
our music collections. At the time I wasn't too thrilled with the idea, thinking
that the computer I was using then was having enough of a challenge with the
task of computing, and the
prospect of this machine handling the job of playing serious high-end music was
certainly not an option. Yet. Yes, the road to being a successful computer
audiophile has sometimes been a rocky one, but with time has come faster, more
reliable computers and software, inexpensive storage, and most of all inventive
audiophile equipment manufactures. Audioengine's $599 D2 24-bit wireless DAC is
truly a 21st Century product that fits well with the needs of a 21st
Century audiophile, as well as any listener who wants the convenience of
high-resolution multi-room playback, all without the need of a home network. The
plug-and-play Audioengine D2 is fun to use, is super reliable, is affordable,
and sounds great. Admit it: you want one.